An openable and closable thread treating nozzle is shown in previously published European patent application Nos. 0184625A1 and 0249804A1 as well as in U.S. Pat. No. 4,941,242, the disclosures of which are incorporated herein by reference in their entireties. An object of the present invention is to provide nozzles of this general type with structures which permit the force for the closing of the thread treating nozzle to be spread homogeneously over the full length of the nozzle.